Neural substrates of low‐frequency repetitive transcranial magnetic stimulation during movement in healthy subjects and acute stroke patients. A PET study

Conchou, Fabrice; Loubinoux, Isabelle; Castel-Lacanal, É.; Tinnier, Anne Le; Gerdelat-Mas, A.; Faure-Marie, Nathalie; Gros‐Dagnac, Hélène; Thalamas, Claire; Calvas, Fabienne; Berry, Isabelle; Chollet, François; Moreau, Marion Simonetta

doi:10.1002/hbm.20690

Cited by 40 publications

(31 citation statements)

References 67 publications

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“…Cerebral perfusion in the sensory-motor ROIs at rest did not change with iTBS confirming previous observations in rTMS/PET studies at rest [Conchou et al, 2008]. This indicates that the BOLD signal decrease is not caused by a global change in brain perfusion within the network and supports the idea that the facilitating effect of iTBS is activity-dependent.…”

Section: Functional Imaging At Restsupporting

confidence: 88%

Exploring the after‐effects of theta burst magnetic stimulation on the human motor cortex: A functional imaging study

Cárdenas-Morales¹,

Grön²,

Kammer³

2010

Human Brain Mapping

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Theta burst stimulation (TBS) is a protocol of subthreshold repetitive transcranial magnetic stimulation (rTMS) inducing changes in cortical excitability. From functional imaging studies with conventional subthreshold rTMS protocols, it remains unclear what type of modulation occurs (direction and dependency to neural activity) and whether putative effects are bound to unspecific changes in cerebral perfusion or require a functional challenge. In a within-subjects (n = 17) repeated measurement design including real TBS and a control session without stimulation, we examined neural activation in a choice-reaction task after application of intermittent TBS, a protocol, which enhances cortical excitability over the left motor cortex (M1). Brain activity was monitored by blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging interleaved with measuring regional cerebral blood flow (rCBF) at rest using MR-based perfusion imaging. On a separate day, TMS-induced compound muscle action potentials (cMAPs) amplitude of the right hand was measured after excitatory TBS. Compared to control, a significant decrease in BOLD signal due to right hand motor activity during the choice-reaction task was observed mainly in the stimulated M1 and motor-related remote areas after stimulation. This decrease might represent a facilitating effect, because cMAPs amplitude increased upon TBS compared to control. No changes in rCBF at rest were observed. The data demonstrate that subthreshold intermittent TBS targets both the stimulated cortical area as well as remote areas. The facilitation changing the efficacy of neural signal transmission seems to be reflected by a BOLD signal decrease, whereas the network at rest does not appear to be affected.

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Section: Functional Imaging At Restsupporting

confidence: 88%

Exploring the after‐effects of theta burst magnetic stimulation on the human motor cortex: A functional imaging study

Cárdenas-Morales¹,

Grön²,

Kammer³

2010

Human Brain Mapping

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“…This pattern was common at all patients in PVS, independently of their etiology ( p FWE corrected Ͻ0.05). Finally, a psychophysiological interaction 1,[16][17][18][19][20] analysis of the activity signal of the left S1M1 cortex (proprioceptive stimulus Ϫ rest) enabled us to demonstrate a loss of functional connectivity between this primary area (left S1M1) and the high-level associative structures recruited by the task (right and left BA 40) in patients, whereas functional connectivity was found in the controls (corrected p value Ͻ0.05; figure 4). Nevertheless, the functional link between these primary and secondary areas was different between the ipsilateral and contralateral sides in patients in PVS (figure 4).…”

Section: Resultsmentioning

confidence: 93%

“…[11][12][13] Then, we performed a functional connectivity analysis. 1,[16][17][18][19][20] The ARAS, whose activity was functionally correlated to that of the precuneus in healthy subjects, showed no correlation with this structure in the patient group (corrected p value Ͻ0.05; figure 2). Comparison of deactivations between the 2 groups showed a significantly smaller degree of deactivation in the precuneus in the patient group than in the control group (SVC of a 12-mmradius sphere applied on precuneus, p FWE corrected Ͻ0.05; figure 3).…”

Section: Resultsmentioning

confidence: 98%

Wakefulness and Loss of Awareness: Brain and Brainstem Interaction in the Vegetative State

Machado¹,

Estévez²,

Redriguez³

et al. 2010

Neurology

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Objective:The ascending reticular activating system (ARAS) modulates circadian wakefulness, which is preserved in a persistent vegetative state (PVS). Its metabolism is preserved. Impairment of metabolism in the polymodal associative cortices (i.e., precuneus) is characteristic of PVS where awareness is abolished. Because the interaction of these 2 structures allows conscious sensory perception, our hypothesis was that an impaired functional connectivity between them participates in the loss of conscious perception. Methods:15 O-radiolabeled water PET measurement of regional cerebral blood flow (rCBF) was performed at rest and during a proprioceptive stimulation. Ten patients in PVS and 10 controls were compared in a cross-sectional study. The functional connectivity from the primary sensorimotor cortex (S1M1) and the ARAS in both groups was also investigated. Results:Compared with controls, patients showed significantly less rCBF in posterior medial cortices (precuneus) and higher rCBF in ARAS at rest. During stimulation, bilateral Brodmann area 40 was less activated and not functionally correlated to S1M1 in PVS as it was in controls. Precuneus showed a lesser degree of deactivation in patients. Finally, ARAS whose activity was functionally correlated to that of the precuneus in controls was not in PVS. Conclusions:Global neuronal workspace theory predicts that damage to long-distance white matter tracts should impair access to conscious perception. During persistent vegetative state, we identified a hypermetabolism in the ascending reticular activating system (ARAS) and impaired functional connectivity between the ARAS and the precuneus. This result emphasizes the functional link between cortices and brainstem in the genesis of perceptual awareness and strengthens the hypothesis that consciousness is based on a widespread neural network. Neurology® 2010;74:313-320 GLOSSARY ARAS ϭ ascending reticular activating system; BA ϭ Brodmann area; DMN ϭ default-mode network; FWE ϭ family-wise error; IPL ϭ inferior parietal lobule; PVS ϭ persistent vegetative state; rCBF ϭ regional cerebral blood flow; S1M1 ϭ primary sensorimotor cortex; SVC ϭ small volume correction.Persistent vegetative state (PVS) describes a unique disorder in which patients who emerge from coma seem to be awake but show no signs of awareness. The ascending reticular activating system (ARAS) is located at a critical juncture in the inflow of sensory information, and its activity modulates circadian wakefulness. No abnormality has been reported in the ARAS in PVS so far. 1 According to some authors, activity in the precuneus is a sign of self-referential processing during which stimulus-independent thought could participate in the emergence of perceptual awareness. Its metabolism is impaired in PVS.2 In healthy subjects, effects of each structure on each other (precuneus and ARAS) exist in the basal state, are opposite, and are thought to predict whether a somatosensory stimulus will be consciously perceived. 3 We found it appropriate to ev...

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“…M1 is involved in both the generation and learning of movement and blood flow during hand movement scales with basic task demands, e.g., tapping frequency (Sadato et al, 1996) and grip force (Sehm, Perez, Xu, Hidler, & Cohen, 2010). One study, (Conchou et al, 2009) found changes in movement-related blood flow in contralateral M1 and connected areas, after inhibitory (1 Hz) rTMS in a comparison to rest. Our paradigm did not contain a resting condition and the motoric demands of the task were constant across conditions.…”

Section: 4 Discussionmentioning

confidence: 99%

Shifts in connectivity during procedural learning after motor cortex stimulation: A combined transcranial magnetic stimulation/functional magnetic resonance imaging study

Steel

Song

Bageac

et al. 2016

Cortex

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Inhibitory transcranial magnetic stimulation, of which continuous theta burst stimulation (cTBS) is a common form, has been used to inhibit cortical areas during investigations of their function. cTBS applied to the primary motor area (M1) depresses motor output excitability via a local effect and impairs procedural motor learning. This could be due to an effect on M1 itself and/or to changes in its connectivity with other nodes in the learning network. To investigate this issue, we used functional magnetic resonance imaging to measure changes in brain activation and connectivity during implicit procedural learning after real and sham cTBS of M1. Compared to sham, real cTBS impaired motor sequence learning, but caused no local or distant changes in brain activation. Rather, it reduced functional connectivity between motor (M1, dorsal premotor & supplementary motor areas) and visual (superior & inferior occipital gyri) areas. It also increased connectivity between frontal associative (superior & inferior frontal gyri), cingulate (dorsal & middle cingulate), and temporal areas. This potentially compensatory shift in coupling, from a motor-based learning network to an associative learning network accounts for the behavioral effects of cTBS of M1. The findings suggest that the inhibitory transcranial magnetic stimulation affects behavior via relatively subtle and distributed effects on connectivity within networks, rather than by taking the stimulated area “offline.”

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Neural substrates of low‐frequency repetitive transcranial magnetic stimulation during movement in healthy subjects and acute stroke patients. A PET study

Cited by 40 publications

References 67 publications

Exploring the after‐effects of theta burst magnetic stimulation on the human motor cortex: A functional imaging study

Exploring the after‐effects of theta burst magnetic stimulation on the human motor cortex: A functional imaging study

Wakefulness and Loss of Awareness: Brain and Brainstem Interaction in the Vegetative State

Shifts in connectivity during procedural learning after motor cortex stimulation: A combined transcranial magnetic stimulation/functional magnetic resonance imaging study

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